1. Field of the Invention
The present invention relates to an optical recording method and an optical recording device for recording data on an optical disc, more particularly to a method of adjusting a write strategy used in recording.
2. Description of the Related Art
In recent years, Blu-ray discs and other large-capacity next-generation optical discs are being used in increasingly many optical recording devices. For stable recording on these types of optical discs, the recording pulse parameters, that is, the write strategy parameters, that are considered optimal for the characteristics of each optical disc are recorded on the optical disc, in the optical recording device, or elsewhere, and optimal settings are made for each disc.
However, when data are recorded on an optical disc, the use of write strategy parameters set for each optical disc as above does not always permit stable recording to be carried out, because of environmental changes such as changes in ambient temperature, and changes in the recording region on the optical disc, that is, the radial position on the optical disc.
As a solution to this problem, Japanese Patent Application Publication No. 2002-312938 (pp. 1-7, FIGS. 1-12) for example, proposes detecting the lengths of pits and lands that are formed by recording data on an optical disc, modifying the write strategy parameters according to the results, and recording data again. In another proposal, made in Japanese Patent Application Publication No. 2006-302332 (pp. 1-23, FIGS. 1-16), for example, data are recorded on an optical disc and the amount of edge shift of each recording pattern is used as an index to adjust, in particular, the write strategy parameters related to the shape of the shortest recording mark. Multi-pulse write strategies for Blu-ray discs and the like are also disclosed in Sharp Technical Journal No. 90, December 2004 (pp. 11-15).
A problem with the technology disclosed by Japanese Patent Application Publication No. 2002-312938 is that it has not been possible to determine which write strategy parameter to modify, because pit lengths and land lengths are influenced by a plurality of parameters in the write strategy.
A problem with the technology disclosed by Japanese Patent Application Publication No. 2006-302332 is that since it adjusts the write strategy parameters related to the shortest recording mark shape, which have a large effect on the jitter value, if it adjusts these write strategy parameters in the wrong direction, because of the high sensitivity of the jitter value, the jitter value degrades substantially, leading to fatal recording degradation and unstable recording.
The present invention addresses the above problems with the object of enabling stable recording at all times without substantial jitter degradation.